JPH02109218A - Manufacture of oxide superconductive wire rod - Google Patents

Abstract

PURPOSE:To enable oxide superconductive wire rod excellent in superconductive characteristics to be manufactured efficiently by diameter reduction processing and heat-treating a compound billet which is obtained by fusing a material oxide to become a superconductor and then solidifying it into a bar-shaped ingot. CONSTITUTION:A bar-shaped ingot of material oxide to become a superconductor is made in advance by casting, and this bar-shaped ingot 1 is arranged at the center inside a mold 2, and next fused liquid of metal 3 to become sheath material is poured into this mold 2 from a crucible 4, and this fused liquid is solidified in the mold 2 so as to make a compound billet 5 having the bar- shaped ingot 1 therein. Next, this compound billet 5 is processed into compound line material such as a round wire, a square wire, or a tape by the methods of extrusion, drawing, swaging, rolling, etc. Hereafter, heat-treatment is applied to this line material in the oxygen contained atmosphere so as to make it into oxide superconductive line material. Hereby, oxide superconductive line material which is high in density and excellent in characteristics such as critical current density, etc., can be manufactured efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing an oxide superconducting wire used for power cables, magnets, power storage links, magnetic shields, and the like.

[Conventional technology and its issues]

Oxide-generating conductors made of alkaline earth metals, rare earth elements, copper, bismuth, thallium, and other elements and oxygen have high critical temperatures and are expected to be used, but these oxide superconductors are generally linear. It is difficult to process, and its production is usually done by filling a metal tube with the raw material oxide powder that will become the superconductor to make a composite vilent, which is then processed to reduce its area to make a composite wire of the desired shape. This was done by subjecting this composite wire to heat treatment to form an oxide superconducting wire.

However, the superconductor layer density of the oxide superconducting wire obtained by the above method is as low as about 70 to 90%, and therefore the obtained wire has a critical current density (hereinafter abbreviated as Jc).
There was a problem that high values of superconducting properties could not be obtained. In addition, especially in the method of manufacturing multicore superconducting wire, multiple pieces of the above-mentioned composite vilent are packed into a large diameter metal pipe,
This is done by a method of surface reduction processing, which requires a large number of steps, is complicated, and has low productivity.

[Means to solve the problem]

The present invention was devised in view of this situation, and an object of the present invention is to provide a method for efficiently manufacturing an oxide superconducting wire having excellent superconducting properties.

That is, the present invention provides a method for manufacturing an oxide superconducting wire in which an oxide superconductor is sheathed with a metal, in which a raw material oxide to become a superconductor is melted, the melt is solidified into a rod-shaped ingot, and then the rod-shaped ingot is is placed in a mold, and a metal melt serving as a sheath material is injected into the mold and solidified to create a composite billet containing the rod-shaped ingot of the oxide, and then this composite billet is shaped into a desired shape. It is characterized in that it is processed to reduce its area to form a composite wire, and then this composite wire is heat-treated in an oxygen-containing atmosphere.

Next, embodiments of the present invention will be specifically described with reference to the drawings.

Figures 1A and 1B are longitudinal and cross-sectional explanatory views, respectively, showing an embodiment of the method of the present invention. In the figure, 1 is a rod-shaped ingot of raw material oxide that will become a superconductor, 2 is a mold, and 3 is a metal that will be a sheath material.

In advance, a rod-shaped ingot 1 of the raw material oxide that will become the superconductor is produced by casting, and this rod-shaped ingot (2) is placed in the center of the mold 2. Then, the metal 3 that will become the sheath material is melted into the mold 2. A liquid is injected from the crucible 4 and the melt is solidified in the mold 2 to produce a composite billet 5 containing the rod-shaped ingot 1, and then this composite billet 5 is extruded, drawn, swaged, rolled, etc. The wire is processed into a composite wire such as a round wire, a square wire, or a tape, and then this wire is heat-treated in an oxygen-containing atmosphere to form an oxide superconducting wire.

FIG. 2 is an explanatory cross-sectional view of a multicore composite billet 6 manufactured by the method of the present invention. The multicore composite billet 6 is
It is manufactured by arranging a plurality of the rod-shaped ingots 1 at predetermined intervals in a mold, and pouring a melt of the metal 3 that will become the sheath material into the mold and solidifying it. 3
The solidified body contains seven rod-shaped ingots.

The raw material oxide that becomes a superconductor in the method of the present invention is, for example, Y-Ba-Cu-0 based oxide superconductor, Y2O
3. B1-3r- refers to a mixture of raw material powders such as BaC0,+ and CuO, which are blended and mixed to have a desired composition.
In the Ca-Cu-0 based oxide superconductor, the raw material powder contains BizOz, 5rCCh, CaCO3 and C
uO etc. are used.

In the method of the present invention, the heating furnace used to cast the oxide that becomes the superconductor into a rod shape includes a high frequency induction heating furnace,
An electric resistance heating furnace, an infrared heating furnace, etc. are used.

The crucible used in the above may be made of materials such as PL, PL gold alloy CaOlMgO, etc. depending on the type of oxide.

In the method of the present invention, the metal container serving as the sheath material contains A
Among these, Ag and Ag alloys are easily permeable to oxygen, so it is difficult to supply oxygen to the superconductor layer during the heat treatment after wire processing. It is well done and desirable.

[Effect]

In the method of the present invention, to produce a composite billet,
The raw material oxide that becomes the superconductor is melted, and this is solidified into a rod-shaped ingot and composited, so the density of the superconductor layer of the oxide superconducting wire obtained by reducing the area and heat treating the resulting composite billet is very close to the true density.

Further, since the metal that becomes the sheath material is melted and composited by casting the rod-shaped ingot, it is possible to save the labor of processing the sheath metal into a vibrator.

〔Example〕

The present invention will be explained in detail below using examples.

Example 1 Raw material powders of Y2O3, BaC0t, and CuO were mixed into Y:Ba:
Cu is weighed and mixed so that the atomic ratio is I:2:3 to obtain a raw material oxide, which is placed in a platinum crucible and heated to 1300'C in an Elema furnace to melt it, and this melt is It was cast into an iron mold to form a rod-shaped ingot with an outer diameter of 10 mm.

Next, as shown in Fig. 1A, the rod-shaped ingot 1 is
was placed in the center of an iron mold 2 with an inner diameter of 23I1111, and a melt of Ag3 heated to 1100°C serving as a sheath material was poured into the mold 2 from a crucible 4 and solidified to produce a composite billet 5. Next, the composite billet 5 was formed into a 0.5 mmφ composite wire by swaging and groove roll rolling, and then this composite wire was rolled in an oxygen stream for 90 minutes.
An oxide superconducting wire was manufactured by heat treatment for 00°CIO time.

Example 2 A composite billet 5 made in the same manner as in Example 1 was rolled into 1. An oxide superconducting wire was manufactured in the same manner as in Example 1, except that a tape-shaped composite wire of 0 mm' was used.

Example 3 Seven rod-shaped ingots of the same superconducting oxide used in Example 1 were placed at equal intervals in an iron mold with an inner diameter of 70++II++, and then heated to 1100°C in this mold. A multicore composite billet 6 as shown in FIG. 2 is produced by injecting and solidifying Ag melt, and then this composite billet 6 is
was processed into a bar with a diameter of 10IIIll by hot isostatic extrusion, followed by a composite wire with a diameter of 1 by groove roll rolling, which was then heat-treated at 900°C for 20 hours in an oxygen stream to produce an oxide superconducting wire. was manufactured.

Comparative Example I Y, O, BaC0+, CuO raw material powders Y:Ba:
The raw material oxides were weighed and mixed so that the atomic ratio of Cu was 1:2:3, and the raw material oxides were calcined in the atmosphere for 900°CIO hours, and then this calcined body was pulverized and classified to form calcined powder, and then Later, this calcined powder was made into Ag with an inner diameter of 10 mm and an outer diameter of 23 mm.
It was filled into a pipe to form a composite billet, and this composite billet was made into an oxide superconducting wire of 0.5 mmφ by the same method as in Example 1.

Comparative Example 2 Composite billet 5 was prepared by filling an Ag pipe with an inner diameter of 23 mm with the same pre-sintered powder as used in Comparative Example I, and seven Ag pipes with an inner diameter of 70 mm were filled with this composite billet. A multicore composite billet was prepared by packing the billet into an oxide superconducting wire having a diameter of 1 mm using the same method as in Example 3.

The relative density and J of each of the oxide superconducting wires thus obtained were measured. The results are shown in Table 1 along with the main manufacturing conditions.

As is clear from Table 1, the method products of the present invention (Examples 1 to 3)
3) all have higher values of J than the comparative method products (Comparative Examples 1 and 2).

This is because the method of the present invention melts the raw material oxide that becomes the superconductor, and then solidifies it into a rod-shaped ingot to create a composite billet, so the density of the superconductor layer of the obtained oxide superconducting wire is extremely high. This is because it has become expensive.

On the other hand, in the comparative product, the pre-sintered powder was filled in the metal container as a powder, so the density of the resulting wire was low and the superconducting properties were poor.

In addition, as described in Comparative Example 1.2, the conventional manufacturing method for oxide superconducting wire requires many complicated steps such as adjusting the pre-sintered powder, producing the Ag pipe, and filling the Ag pipe with the pre-sintered powder. In short, it can be seen that the productivity is inferior to the method of the present invention shown in Examples 1 to 3.

Although the Y-based oxide superconducting wire has been described above, it goes without saying that the method of the present invention can also be applied to other oxide superconducting wires such as Bl-based.

〔effect〕

As described above, according to the method of the present invention, the density is high and the J
Since oxide superconducting wires having excellent characteristics such as c can be efficiently produced, this method has a significant industrial effect.

[Brief explanation of drawings]

FIG. 1A is a vertical and cross-sectional explanatory view showing an embodiment of the method of the present invention, and FIG. 2 is a cross-sectional view of a multicore composite billet. 1... Rod-shaped ingot of raw material oxide, 2... Mold, 3
...Metal as sheath material, 4...Crucible,
5... Composite billet, 6... f' core composite billet.

Claims (1)

[Claims] In a method for manufacturing oxide superconducting wire in which an oxide superconductor is sheathed with metal, the raw material oxide that becomes the superconductor is melted, solidified into a rod-shaped ingot, and then this rod-shaped ingot is placed in a mold. Then, a molten metal that will become a sheath material is injected into this mold and solidified to produce a composite billet containing the rod-shaped ingot of the oxide, and then this composite billet is subjected to area reduction processing into a desired shape. A method for producing an oxide superconducting wire, which comprises forming a composite wire and then heat-treating the composite wire in an oxygen-containing atmosphere.